1. Field of the Invention
The present invention relates to an offshore well test platform and, more particularly, to a well test platform that is supported by a submerged buoy.
2. Description of the Prior Art
In the offshore exploration for hydrocarbons, after a discovery has been made, numerous well tests are conducted to evaluate the economic potential of the reservoir to produce hydrocarbons therefrom economically. To perform these well tests, a stable platform is needed to support equipment, storage tanks and personnel. A vessel can be preferably dynamically positioned above the wells and then interconnected via a riser to the well to conduct such well test or workover operations. Such vessels are expensive to use on long duration tests and are very difficult to work on due to wind and wave-induced heave, roll, and pitch motions. An alternative is to utilize simple well protector jacket structures; however, these structures are feasible only in shallow water. In deeper waters, a fixed well protector platform or structure may be constructed and installed above the well. While a fixed platform is not affected by wind and wave induced motion, a platform of this type is a very expensive investment. Because, if the platform is installed and from the well tests conducted the reservoir is economically unproductive, then the cost of such a platform has been wasted.
There is a need for an inexpensive, stable well test platform which, if desired, can be easily removed and placed in other locations in deep waters.
One type of well test platform, which is shown in FIG. 1, includes two buoys vertically aligned with one at the surface and one below the surface of the water, and which are anchored to the subsea floor by a single tensioned rigid riser in the same manner as a tension leg platform (TLP). One of the major concerns of the use of this type of well test platform is that while there is little or no heave motion, there can be unacceptable angular or pitching motion. Also, it is not capable of servicing multiple wells.